I have created a private network of ethereum block chain. The network is open for anybody to join and run their own node.
But I dont want them to mine blocks. I Want to restrict mining to certain nodes.
Any lead is appreciated.
There are Proof of Authority (PoA) consensus algorithms for parity and geth. With PoA you can explicitly specify who is allowed to mine/seal blocks.
For a step-by-step guide for geth's clique PoA, see https://hackernoon.com/setup-your-own-private-proof-of-authority-ethereum-network-with-geth-9a0a3750cda8